Variable voltage transformer



J1me 1965 w. KOBER 3,187,283

VARIABLE VOLTAGE TRANSFORMER Filed July 5, 1961 Fi .1. m Q 1 9 22 I /20 4 1.3-4.

INVENTOR.

William Kobar,

ATTORNEYS United States Patent 0 3,187,283 VAREAELE VGLT AGE TRANSFORMER William fisher, Fairport, N.Y., assignor, by mesne assi ments, to The Garrett Corporation, Los Angeies, Calif, a corporation of Qalifornia Filed July 5, 1961, Ser. No. 121,874 in Claims. (Cl. 336-119) This invention is directed to the transformer art, and more specifically to a new and useful variable voltage transformer. While not limited thereto, the transformer of my invention is particularly adapted for use as an induction regulator.

Induction regulators having a continuous magnetic-corepath on which the windings form an annular or unbroken series of alternating poles on the primary and secondary cores are well known. However, the transformer regulator of my invention is distinguished from such prior art regulators, in that its primary and secondary magnetic cores are linear and therefore discontinuous as distinguished from ring-like. This lack of symmetry, or discontinuity, creates certain problems, which are solved by my invention.

Thus, it is desired that the secondary have a very low leakage reactance, or impedance at all settings of the transformer regulator. For this purpose, a short circuited damper or compensating winding is needed on the primary, at an axis positioned at 90 electrical degrees to the primary flux path. However, the provision of such a winding presents a problem because of the non-symmetrical nature of my regulator.

Also, it is desired to have a complete flux path between the primary and secondary cores at all relative positions thereof. This, too, presents a problem because of the discontinuous nature of the transformer secondary ofmy invention.

Accordingly, the primary object of my invention is to provide a nonsymmetrical induction regulator transformer providing a complete flux path and having a low I secondary impedance at all settings.

Another object of my invention is to provide an induction regulator transformer requiring no hearings or other suspension means, which is relatively simple and inexpensive in construction while being extremely durable and dependable in operation, and which is relatively compact and light in weight.

In one aspect thereof, a transformer constructed in accordance with my invention is characterized by the provision of a primary core having a discontinuous series of alternating poles, a secondary core operatively associated with the primary core and also having a discontinuous series of alternating poles, the secondary core having one more pole than the primary core, primary and secondary windings associated with the respective cores, and one of the primary and secondary cores being movable relative to the other to vary the voltage induced in the secondary.

In another aspect thereof, a transformer constructed in accordance with my invention is characterized by the provision of a primary core having a discontinuous series of alternating poles created by the windings on the core, a secondary core also having a discontinuous series of alternating poles also created by the placement of the windings thereon, namely the primary and secondary windings associated with the respective cores, one of the primary and secondary cores being movable relative to the other, and a compensating winding associated with the primary core and arranged in a pole pattern centered between adjacent primary poles.

The foregoing and other objects, advantages and characterizing features of a transformer of my invention will "ice become clearly apparent from the ensuing detailed description of one, presently preferred embodiment thereof, considered in conjunction with the accompanying drawing wherein like reference numerals denote like parts throughout the several views, all of which are generally schematic, and wherein:

FIG. 1 is a side elevational view of a transformer of my invention, showing the primary fixed in one extreme position relative to the secondary and indicating, in broken lines, the opposite extreme position thereof;

FIG. 2 is a plan view of the working end face of the primary;

FIG. 3 is a similar plan view, but showing the working end face of the secondary; and

FIG. 4 is a fragmentary view indicating an arrangement for selectively shifting the position of the primary relative to the secondary.

Referring now in detail to the illustrative embodiment depicted in the accompanying drawing, it will be seen that there is provided a primary core 1 and a secondary core 2. The primary and secondary cores 1, 2 can comprise two stacks of flat, toothed laminations, which can be produced by punching, and with the toothed faces of the primary and secondary being in sliding, working contact. With this arrangement, no bearing or other suspension is needed, and a simple and economical construction is provided.

Primay windings 3 and i are distributed in the slots on the toothed working surface of primary 1, in a manner defining a pair of alternating poles. A winding showing 6 slots per pole and two coils per pole is shown for purposes of ill stration, but other numbers of slots and coils can be chosen according to the rules known to the art. FEGS. 2 and 3 show the winding as a continuous wire for clarity of illustration but the winding will normally consist of coils of a number of turns, with ends properly connected. FIG. 1 shows the positions of the coils in the slots, since this more clearly describes the arrangement in this view. Windings 3 and d are oppositely wound and connected in series to comprise a primary winding 3, 4 having leads 5 and 6 adapted for connection to a source of primary voltage, not shown. Secondary windings 7, 8 and h are distributed in the slots on the toothed working face of the secondary 2, in a manner providing three alternating poles. Windings '7 and 9 are wound in the same sense, in opposition to winding 8, and the windings '7, 8 and 9 are connected in series to comprise a secondary winding having leads it and 11 adapted for connection to a load, not illustrated. Thus, the primary and secondary working faces are divided, by the distributed windings 3, 4, 7, 8 and 9 into alternating poles of equal section or area, with the secondary having one more pole than the primary.

It will be observed that, in accordance with my invention, the primary windings 3 and 4 pass around the opposite ends of the laminated block comprising the primary core 1. This eliminates the end slots which normally would be provided for the primary windings, and thereby eliminates two additional teeth on the primary for economy in material and space. Similarly, the secondary windings '7 and 9 pass around the opposite ends of the laminated block comprising the secondary core 2, thereby eliminating the end teeth which would be necessary to provide opposite end slots for these windings.

The primary core 1 is movable between one extreme position relative to the secondary, wherein the primary poles are in working contact with the secondary poles defined by windings 8 and 9 as illustrated in solid lines in PEG. 1, to an opposite extreme position, indicated in phantom, in which the primary poles are in working contact with the secondary poles defined by windings 7 and 8.

In this way, the setting of the transformer can be selectively varied, giving in the illustrated example a smoothly variable full plus to minus swing in the net voltage induced in the secondary winding '7, 8, 9.

, A complete flux path is provided at all positions of the primary, despite the discontinuous nature of the secondary, by providing the secondary with N;l1 poles where N equals the number of poles on the primary. The primary is permitted to move relative to the secondary, or vice versa, a distance equal to a full pole pitch to provide a complete phase swing, and. the secondary will complete a flux path for the primary at all working positions of the latter. Thus, the end problem posed by the discontinuous secondary is solved by my invention.

Low secondary impedance is desired at all working positions of the primary, and therefore a compensating winding must be provided on the primary about an axis at 90 electrical degrees to the axis of the primary winding. This is complicated by the discontinuous nature of the primary presenting an end problem which is solved by the instant invention as follows. A compensating winding comprising individual short circuited loops i2, 13, 14, i5, 16 and i7 is arranged in the primary slots, in a pole pattern centered between the primary poles, on the center line of the illustrated primary which is a line through the central primary tooth 18. Thus, the short circuited winding 12%? defines a pole on an axis at 90 electrical degrees to the primary axis, being positioned midway between the primary poles as defined by windings 3 and 4-.

i The short circuited loops 12-17 are of varying pitch, beginning with an underpitched loop 12 and passing through a full pitch loop 14 to an overpitch winding 17 Y which completely encircles both primary poles, passing outside or around all of the primary teeth. This overpitching and underpitching of the compensating winding blocks the 90 axis to flux produced by transformer secondary currents at all relative working positions of the primary and secondary, between the two extremes depicted in FIG. 1.

The primary core it can be shifted by hand, and then clamped into position by means such as a plate 19 bearing against primary 1 and held thereagainst. Plate 19 is apertured to receive posts 2d extending from a base 21, being releasably fastened thereon as by nuts 22.

Alternately, a rack 23 can be connected to primary 1, and engage a pinion 24 for shifting the primary as more fully set forth in my pending application Serial No. 112,- 447, filed May 24, 1961. The primary can be held in contact with secondary 2, as by a spring 25 secured to a relatively fixed part Edwhich could be part of an enclosing housing.

Of course, the secondary could be arranged for movement relative to the primary.

Accordingly, it is seen that my invention fully accomplishes its intended objects. While I have disclosed and described in detail only one embodiment thereof, that has been done by way of illustration only and without thought of limitation. Many variations therein and modifications thereof are possible and will occur to those skilled in the art, and it is my intention that the scope of my invention be defined by the appended claims.

Having fully disclosed and completely described my invention, and its mode of operation, what I claim as new is:

1. A transformer comprising first and second permeable cores both having similar parallel slots in one face separating a plurality of teeth and these faces of the cores abutting in mutual sliding engagement at the ends of the teeth; primary windings inserted in the slots of the first core and interconnected to energize at least two magnetic poles therein, each pole having a pitch encompassing the same predetermined number of teeth and the polarities of the poles alternating; secondary windings in the slots of the second core and interconnected to energize alternating magnetic poles therein, each pole having the same pitch as those on the first core and there being at least one more pole in the second core than in the first, and means for sliding one core relative to the other in a direction normal to the direction of the slots.

2. in a transformer as set forth in claim 1, compensating winding means including plural short-circuited windings laid in the slots of said first core and offset electrical degrees from the centers of the primary windings on the poles of the first core.

3. In a transformer as set forth in claim 2, said winding means including equally-pitched short-circuited turns set in slots separated by the same predetermined number of teeth.

4. In a transformer as set forth in claim 3, said winding means including other short-circuit turns set in other slots of the first core to provide both under-pitched and overpitched windings each symmetrically disposed with respect to said equally-pitched turns. 7

5. A transformer comprising first and second permeable cores both having parallel slots in one face separating a plurality of teeth and these faces of the cores abutting in mutual sliding engagement at the ends of the teeth; primary windings inserted in the slots of the first core and interconnected to energize at least two magnetic poles therein, each pole encompassing the same'predetermined number of teeth and the polarities of the poles alternating; secondary windings in the slots of the second core and interconnected to energize alternating magnetic poles therein, there being at least one more pole'in the second core than in the first, and compensating winding means including plural short-circuited turns laid in the slots of said first core and offset 90 electrical degrees from the centers of the primary windings on the poles of the first core.

6; The transformer set forth in claim 5, wherein the primary and secondary poles have the same pole pitch.

' '7. The transformer as set forth in claim 5, wherein the primary windings extend around the ends of the first core and the secondary windings extend around the ends of the second core.

8. in a transformer as set forth in claim 5, said winding means including equally-pitched short-circuited turns set in slots separated by the same predetermined number of teeth. 1

9. in a transformer as set forth in claim 8, said winding means including other short-circuited turns set in other slots of the first core to provide both under-pitched and over-pitched windings each symmetrically disposed with respect to said equally-pitched turns.

10. In a transformer as set forth in claim 9, the overpitched windings extending completely around two 0pposite poles of the first core.

References Cited by the Examiner UNITED STATES PATENTS 1,790,746 2/31 Fischer 336 -77 1,942,481 1/34 Lobl 336119 X 2,609,531 9/52 Kirchner 336-419 X JOHN F. BURNS, Primary Examiner. 

1. A TRANSFORMER COMPRISING FIRST AND SECOND PERMEABLE CORES BOTH HAVING SIMILAR PARALLEL SLOTS IN ONE FACE SEPARATEING A PLURALITY OF TEETH AND THESE FACES OF THE CORES ABUTTING IN MUTUAL SLIDING ENGAGEMENT AT THE ENDS OF THE TEETH; PRIMARY WINDINGS INSERTED IN THE SLOTS OF THE FIRST CORE AND INTERCONNECTED TO ENERGIZE AT LEAST TWO MAGNETIC POLES THEREIN, EACH POLE HAVING A PITCH ENCOMPASSING THE SAME PREDETERMINED NUMBER OF TEETH AND THE POLARITIES OF THE POLES ALTERNATING; SECONDARY WINDINGS IN THE SLOTS OF THE SECOND CORE AND INTERCONNECTED TO ENERGIZE ALTERNATING MAGNETIC POLES THEREIN, EACH POLE HAVING THE SAME PITCH AS THOSE IN THE FIRST CORE AND THERE BEING AT LEAST ONE MORE POLE IN THE SECOND CORE THAN IN THE FIRST, AND MEANS FOR SLIDING ONE CORE RELATIVE TO THE OTHER IN A DIRECTION NORMAL TO THE DIRECTION OF THE SLOTS. 